An effective refractive index measurement method, device and equipment

Abstract

The present invention provides a method, device and equipment for measuring effective refractive index. The effective refractive index measuring equipment includes: a light source unit, a coupling and splitting unit, and a light detection unit that are sequentially arranged on the optical path; and a processing unit electrically connected to the light detection unit. The light source unit can be connected to the input end of the optical fiber to be measured. The coupling and splitting unit can clamp the optical fiber to be measured and couple out the light of each mode in the optical fiber to be measured from the fiber core and split it to different spatial directions and positions. The light detection unit can obtain the distances from at least two light power detectors in the light detection unit to the plane where the exposed surface of the optical fiber to be measured is located, and the light powers corresponding to the distances. Different distances correspond to different spatial directions and positions. The processing unit can obtain the effective refractive index corresponding to each mode in the optical fiber to be measured according to the distances and the light powers. This solution solves the problem in the prior art that it is impossible to directly measure the effective refractive index of the modes in a few-mode optical fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of measurement, and particularly to a method, apparatus and device for measuring effective refractive index. Background Art

[0002] With the continuous increase of network users and the emergence of new network data services, the demand for network capacity is growing continuously. Since the common optical multiplexing dimensions (time, wavelength, polarization, multi-level modulation, etc.) have all faced the bottleneck of potential development, the current optical communication system based on ordinary single-mode fiber can no longer meet the booming network capacity demand. And the modes in few-mode fiber (FMF) have received extensive attention as a new optical multiplexing dimension. In an ideal case, each mode is orthogonal to each other and can be used as an independent channel. By performing multi-dimensional multiplexing with traditional time, wavelength, polarization, and multi-level modulation formats, the transmission capacity of the system can be greatly increased, and it can be widely applied in key scenarios such as slicing packet network (SPN), optical transport network (OTN), passive optical network (PON), 5G front-haul, and data center optical interconnection (DCI) in the future.

[0003] For a mode division multiplexing (MDM) optical transmission system, the effective refractive index (Effective refractive index, n eff ) of each mode in the few-mode fiber is an extremely important parameter. The crosstalk level between each mode is directly negatively correlated with the effective refractive index difference (Δn eff ) between each mode. Therefore, it is very important to accurately measure the effective refractive index of the modes in the few-mode fiber. However, as the most critical characteristic parameter of the few-mode fiber, there is currently no direct measurement scheme. The existing effective refractive index measurement schemes are all indirect measurement methods, that is, first measure the refractive index distribution of the fiber, and then simulate and calculate the effective refractive index of each mode according to the measured refractive index distribution. The effective refractive index obtained by this method is limited by the measurement accuracy of the measured refractive index and the simulation accuracy, and there will be a certain difference from the actual value, and the size of the difference is difficult to evaluate.

[0004] Specifically, when viewed in the transmission direction of the optical fiber, there are slight refractive index perturbations (affected by materials and manufacturing processes). In theory, the optical fiber is a perfect circular symmetric structure, but in reality, there are differences in all directions. In the prior art, only the refractive index distribution in one diameter direction is measured during refractive index measurement, so it is impossible to accurately obtain the refractive index information of the entire optical fiber cross-section, which in turn causes a certain degree of inaccuracy in the calculation. It can be seen that the existing effective refractive index measurement schemes for modes in few-mode optical fibers cannot obtain the direct measured value of the effective refractive index, but only indirect analysis values. Therefore, researching and testing the effective refractive index of modes in few-mode optical fibers has great practical significance for mode division multiplexing optical transmission systems.

[0005] As can be seen from the above, it is impossible to directly measure the effective refractive index of modes in few-mode optical fibers in the prior art. Summary of the Invention

[0006] The purpose of the present invention is to provide a method, device, and equipment for measuring the effective refractive index to solve the problem that it is impossible to directly measure the effective refractive index of modes in few-mode optical fibers in the prior art.

[0007] To solve the above technical problems, an embodiment of the present invention provides an effective refractive index measurement device, including:

[0008] A light source unit, a coupling and splitting unit, and a light detection unit arranged in sequence on the optical path; and a processing unit electrically connected to the light detection unit;

[0009] Among them, the light source unit can be connected to the input end of the optical fiber to be measured;

[0010] The coupling and splitting unit can clamp the optical fiber to be measured and couple out the light of each mode in the optical fiber to be measured from the core and split it to different spatial directions and positions;

[0011] The light detection unit can obtain at least two groups of distances from the light power detection components in the light detection unit to the plane where the exposed surface of the optical fiber to be measured is located, and the light power corresponding to the distances; different ones of the distances correspond to different spatial directions and positions;

[0012] The processing unit can obtain the effective refractive index corresponding to each mode in the optical fiber to be measured according to the distances and the light power.

[0013] Optionally, the coupling and splitting unit includes: a grooved pad and a prism covering the grooved pad;

[0014] Among them, the optical fiber to be measured is fixed in the groove of the grooved pad, and the exposed surface of the optical fiber to be measured is adjacent to the prism.

[0015] Optionally, a refractive index matching liquid layer is provided between the exposed surface of the optical fiber to be measured and the prism; the refractive index matching liquid layer enables the light emitted from the prism to hit the plane where the optical power detection component in the optical detection unit is located.

[0016] Optionally, the optical detection unit further includes: a displacement stage connected to the optical power detection component;

[0017] wherein, the optical power detection component can move in the vertical direction on the displacement stage.

[0018] Optionally, the displacement stage includes a base and a rod provided on the base; the optical power detection component is sleeved on the rod.

[0019] An embodiment of the present invention further provides an effective refractive index measurement method, which is applied to the above-mentioned effective refractive index measurement device, and the method includes:

[0020] Inputting an optical signal into the optical fiber to be measured by using a light source unit to obtain the light of each mode in the optical fiber to be measured;

[0021] Coupling the light of each mode in the optical fiber to be measured out of the fiber core by using a coupling and splitting unit, and splitting it to different spatial directions and positions;

[0022] Detecting the optical power in the different spatial directions and positions by using an optical detection unit to obtain at least two sets of distances from the optical power detection component in the optical detection unit to the plane where the exposed surface of the optical fiber to be measured is located, and the optical power corresponding to the distances;

[0023] Obtaining the effective refractive index corresponding to each mode in the optical fiber to be measured by using a processing unit according to the distances and the optical power.

[0024] Optionally, the obtaining the effective refractive index corresponding to each mode in the optical fiber to be measured by using a processing unit according to the distances and the optical power includes:

[0025] Using a processing unit to obtain at least one maximum value and the distance corresponding to the maximum value from at least two of the optical powers;

[0026] Obtaining the effective refractive index corresponding to each mode in the optical fiber to be measured according to the at least one maximum value and the distance corresponding to the maximum value.

[0027] Optionally, the obtaining the effective refractive index corresponding to each mode in the optical fiber to be measured according to the at least one maximum value and the distance corresponding to the maximum value includes:

[0028] Using Formulas 1 to 4, based on the maximum value and the distance corresponding to the maximum value, obtain the effective refractive index corresponding to the respective mode in the fiber under test;

[0029] Among them, the Formulas 1 to 4 are as follows:

[0030] n 1 sin(θ 1 )=n 2 sin(θ 2 );

[0031]

[0032]

[0033]

[0034] The n 1 represents the refractive index of the prism of the coupling beam splitting unit at the working wavelength of the light source unit; the θ 1 represents the angle between the light emerging from the exposed surface of the fiber under test and the upper surface of the grooved spacer block of the coupling beam splitting unit within the prism; the n 2 represents the refractive index of air at the working wavelength of the light source unit; the θ 2 represents the angle between the light emerging from the prism and the upper surface of the grooved spacer block; the h 1 represents the distance from the light exit point on the exit surface of the prism to the bottom edge of the exit surface; the d 1 represents the distance from the center point of the exposed surface of the fiber under test to the bottom edge of the exit surface; the h 2 represents the distance corresponding to the maximum value; the d 2 represents the distance from the exit surface to the plane where the optical power detection component in the optical detection unit is located; the n eff represents the effective refractive index;

[0035] The upper surface of the grooved spacer block refers to the surface adjacent to the prism.

[0036] An embodiment of the present invention further provides an effective refractive index measurement device, which is applied to the above-mentioned effective refractive index measurement equipment. The device includes:

[0037] A first input module, configured to input an optical signal into the fiber under test by using a light source unit to obtain light of each mode in the fiber under test;

[0038] A coupling beam splitting module, configured to couple the light of each mode in the fiber under test out of the fiber core by using a coupling beam splitting unit and split it into different spatial directions and positions;

[0039] A first detection module, configured to detect the optical powers in different spatial directions and positions by using an optical detection unit, so as to obtain the distances from at least two optical power detectors in the optical detection unit to the plane where the exposed surface of the optical fiber to be measured is located, and the optical powers corresponding to the distances.

[0040] A first processing module, configured to obtain the effective refractive indices corresponding to the respective modes in the optical fiber to be measured by using a processing unit according to the distances and the optical powers.

[0041] Optionally, the obtaining the effective refractive indices corresponding to the respective modes in the optical fiber to be measured by using the processing unit according to the distances and the optical powers includes:

[0042] Using the processing unit to obtain at least one maximum value from at least two of the optical powers and the distance corresponding to the maximum value;

[0043] Obtaining the effective refractive indices corresponding to the respective modes in the optical fiber to be measured according to the at least one maximum value and the distance corresponding to the maximum value.

[0044] Optionally, the obtaining the effective refractive indices corresponding to the respective modes in the optical fiber to be measured according to the at least one maximum value and the distance corresponding to the maximum value includes:

[0045] Adopting Formula 1 to Formula 4 to obtain the effective refractive indices corresponding to the corresponding modes in the optical fiber to be measured according to the maximum value and the distance corresponding to the maximum value;

[0046] Wherein, the Formula 1 to Formula 4 are as follows:

[0047] n 1 sin(θ 1 )=n 2 sin(θ 2 );

[0048]

[0049]

[0050]

[0051] The n 1 represents the refractive index of the prism of the coupling beam splitting unit at the working wavelength of the light source unit; the θ 1 represents the angle between the light transmitted from the exposed surface of the optical fiber to be measured and the upper surface of the grooved spacer of the coupling beam splitting unit in the prism; the n 2 represents the refractive index of air at the working wavelength of the light source unit; the θ 2denotes the angle between the light emerging from the prism and the upper surface of the slotted spacer; the h 1 denotes the distance from the light-emitting point on the light-emitting surface of the prism to the bottom edge of the light-emitting surface; the d 1 denotes the distance from the center point of the exposed surface of the fiber under test to the bottom edge of the light-emitting surface; the h 2 denotes the distance corresponding to the maximum value; the d 2 denotes the distance from the light-emitting surface to the plane where the optical power detector in the optical detection unit is located; the n eff denotes the effective refractive index;

[0052] The upper surface of the slotted spacer refers to the surface adjacent to the prism.

[0053] An embodiment of the present invention further provides an effective refractive index measurement device, including the components included in the above-mentioned effective refractive index measurement device. The device further includes: a processor and a transceiver;

[0054] The processor is configured to input an optical signal into the fiber under test by using a light source unit to obtain the light of each mode in the fiber under test;

[0055] Using a coupling and splitting unit to couple the light of each mode in the fiber under test out of the core and split it into different spatial directions and positions;

[0056] Using an optical detection unit to detect the optical power in the different spatial directions and positions, obtaining at least two distances from the optical power detector in the optical detection unit to the plane where the exposed surface of the fiber under test is located, and the optical power corresponding to the distance;

[0057] Using a processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distance and the optical power.

[0058] Optionally, the step of using a processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distance and the optical power includes:

[0059] Using a processing unit to obtain at least one maximum value from at least two of the optical powers and the distance corresponding to the maximum value;

[0060] According to the at least one maximum value and the distance corresponding to the maximum value, obtaining the effective refractive index corresponding to each mode in the fiber under test.

[0061] Optionally, the step of obtaining the effective refractive index corresponding to each mode in the fiber under test according to the at least one maximum value and the distance corresponding to the maximum value includes:

[0062] Using Formulas 1 to 4, based on the maximum value and the distance corresponding to the maximum value, obtain the effective refractive index corresponding to the corresponding mode in the optical fiber to be measured;

[0063] Among them, Formulas 1 to 4 are as follows:

[0064] n 1 sin(θ 1 ) = n 2 sin(θ 2 );

[0065]

[0066]

[0067]

[0068] The n 1 represents the refractive index of the prism of the coupling beam splitting unit at the working wavelength of the light source unit; the θ 1 represents the angle between the light emerging from the exposed surface of the optical fiber to be measured inside the prism and the upper surface of the grooved spacer of the coupling beam splitting unit; the n 2 represents the refractive index of air at the working wavelength of the light source unit; the θ 2 represents the angle between the light emerging from the prism and the upper surface of the grooved spacer; the h 1 represents the distance from the light exit point on the exit surface of the prism to the bottom edge of the exit surface; the d 1 represents the distance from the center point of the exposed surface of the optical fiber to be measured to the bottom edge of the exit surface; the h 2 represents the distance corresponding to the maximum value; the d 2 represents the distance from the exit surface to the plane where the optical power detection component in the light detection unit is located; the n eff represents the effective refractive index;

[0069] The upper surface of the grooved spacer refers to the surface adjacent to the prism.

[0070] An embodiment of the present invention further provides an effective refractive index measurement device, including a memory, a processor, and a program stored on the memory and executable on the processor; when the processor executes the program, the above-mentioned effective refractive index measurement method is implemented.

[0071] An embodiment of the present invention further provides a readable storage medium, on which a program is stored, and when the program is executed by a processor, the steps in the above-mentioned effective refractive index measurement method are implemented.

[0072] The beneficial effects of the above technical solutions of the present invention are as follows:

[0073] In the above solution, the effective refractive index measuring device is set up as follows: a light source unit, a coupling and splitting unit, and a light detection unit that are sequentially arranged on the optical path; and a processing unit that is electrically connected to the light detection unit. Among them, the light source unit can be connected to the input end of the optical fiber to be measured; the coupling and splitting unit can clamp the optical fiber to be measured and couple the light of each mode in the optical fiber to be measured out of the core and split it into different spatial directions and positions; the light detection unit can obtain at least two groups of distances from the light power detection components in the light detection unit to the plane where the exposed surface of the optical fiber to be measured is located, and the light power corresponding to the distances; different distances correspond to different spatial directions and positions; the processing unit can obtain the effective refractive index corresponding to each mode in the optical fiber to be measured according to the distances and the light power; it can directly, simply, and accurately measure the effective refractive index of each mode in a few-mode optical fiber at the same time, and well solve the problem that the direct measurement of the effective refractive index of the mode in a few-mode optical fiber cannot be achieved in the prior art. Description of the Drawings

[0074] Figure 1 Structural schematic of the effective refractive index measuring device according to an embodiment of the present invention Figure 1 ;

[0075] Figure 2 Flow schematic of the effective refractive index measuring method according to an embodiment of the present invention;

[0076] Figure 3 Front view schematic of the coupling and splitting unit and the light detection unit according to an embodiment of the present invention;

[0077] Figure 4 Top view schematic of the coupling and splitting unit and the light detection unit according to an embodiment of the present invention;

[0078] Figure 5 Assembly relationship schematic of the optical fiber to be measured and the coupling and splitting unit according to an embodiment of the present invention;

[0079] Figure 6 Relationship schematic of the output light power of the optical fiber to be measured and the measurement height information according to an embodiment of the present invention;

[0080] Figure 7 Structural schematic of the effective refractive index measuring device according to an embodiment of the present invention;

[0081] Figure 8 Structural schematic of the effective refractive index measuring device according to an embodiment of the present invention Figure 2 。 Detailed Embodiments

[0082] To make the technical problems, technical solutions, and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0083] In view of the problem in the existing technology that the direct measurement of the effective refractive index of modes in few-mode optical fibers cannot be achieved, the present invention provides an effective refractive index measurement device. As shown in Figure 1 , Figure 3 and Figure 4 , it includes:

[0084] A light source unit 1, a coupling and splitting unit 2, and a light detection unit 3 that are sequentially arranged on the optical path; and a processing unit 4 that is electrically connected to the light detection unit 3;

[0085] Among them, the light source unit 1 can be connected to the input end of the optical fiber 5 to be measured;

[0086] The coupling and splitting unit 2 can clamp the optical fiber 5 to be measured and couple the light of each mode in the optical fiber 5 to be measured out of the fiber core and split it to different spatial directions and positions;

[0087] The light detection unit 3 can obtain at least two groups of distances h from the light power detection components 6 in the light detection unit 3 to the plane of the exposed surface 7 of the optical fiber 5 to be measured 2 , and the light power corresponding to the distance h 2 ; different distances h 2 correspond to different spatial directions and positions;

[0088] The processing unit 4 can obtain the effective refractive index corresponding to each mode in the optical fiber 5 to be measured according to the distance h 2 and the light power.

[0089] Among them, the fiber core is the fiber core of the optical fiber to be measured, and the light power detection component can specifically be a light power meter. In the embodiment of the present invention, the effective refractive index n eff refers to: in a waveguide structure, at a certain wavelength, the ratio of the propagation constant β of the mode corresponding to the wavelength λ to the vacuum wave number (2π / λ); that is, β = n eff ×(2π / λ).

[0090] The effective refractive index measurement device provided by the embodiments of the present invention is configured as follows: a light source unit, a coupling and splitting unit, and a light detection unit that are sequentially arranged on the optical path; and a processing unit that is electrically connected to the light detection unit. The light source unit can be connected to the input end of the fiber to be measured. The coupling and splitting unit can hold the fiber to be measured and couple out the light of each mode in the fiber to be measured from the core and split it to different spatial directions and positions. The light detection unit can obtain at least two sets of distances from the light power detection components in the light detection unit to the plane where the exposed surface of the fiber to be measured is located, and the light power corresponding to the distances. Different distances correspond to different spatial directions and positions. The processing unit can obtain the effective refractive index corresponding to each mode in the fiber to be measured according to the distances and the light power, and can directly, simply, and accurately measure the effective refractive index of each mode in a few-mode fiber at the same time, which well solves the problem in the prior art that the direct measurement of the effective refractive index of the mode in a few-mode fiber cannot be achieved.

[0091] As Figures 3 to 5 shown, the coupling and splitting unit 2 includes: a grooved spacer 8 and a prism 9 covering the grooved spacer 8. The fiber to be measured 5 is fixed in the groove 10 of the grooved spacer 8, and the exposed surface 7 of the fiber to be measured 5 is adjacent to the prism 9.

[0092] In this way, the light in the fiber can be well coupled and split.

[0093] Specifically, the fiber to be measured can be fixed in the groove with glue.

[0094] As Figures 3 to 5 shown, a refractive index matching liquid layer 11 is provided between the exposed surface 7 of the fiber to be measured 5 and the prism 9. The refractive index matching liquid layer 11 enables the light emitted by the prism 9 to hit the plane where the light power detection component 6 in the light detection unit 3 is located.

[0095] In this way, it can be ensured that the light detection unit can accurately detect the optical signal.

[0096] As Figure 3 and Figure 4 shown, the light detection unit 3 further includes: a displacement stage 12 connected to the light power detection component 6. The light power detection component 6 can move vertically on the displacement stage 12.

[0097] In this way, it can be ensured that the light power detection component detects the optical signals at different positions and spatial directions.

[0098] As Figure 3 and Figure 4As shown, the displacement stage 12 includes a base 13 and a rod 14 disposed on the base 13; the optical power detector 6 is sleeved on the rod 14.

[0099] This can ensure the movement of the optical power detector.

[0100] An embodiment of the present invention also provides an effective refractive index measurement method, which is applied to the above-mentioned effective refractive index measurement device, such as Figure 2 As shown, the method includes:

[0101] Step 21: Input an optical signal into the fiber under test by using the light source unit to obtain the light of each mode in the fiber under test;

[0102] Step 22: Use the coupling and splitting unit to couple the light of each mode in the fiber under test out of the core and split it to different spatial directions and positions;

[0103] Step 23: Use the light detection unit to detect the optical power in the different spatial directions and positions, obtain at least two distances from the optical power detector in the light detection unit to the plane where the exposed surface of the fiber under test is located, and the optical power corresponding to the distance;

[0104] Step 24: Use the processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distance and the optical power.

[0105] The effective refractive index measurement method provided by the embodiment of the present invention inputs an optical signal into the fiber under test by using the light source unit to obtain the light of each mode in the fiber under test; uses the coupling and splitting unit to couple the light of each mode in the fiber under test out of the core and split it to different spatial directions and positions; uses the light detection unit to detect the optical power in the different spatial directions and positions, obtain at least two distances from the optical power detector in the light detection unit to the plane where the exposed surface of the fiber under test is located, and the optical power corresponding to the distance; uses the processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distance and the optical power; it can directly, simply and accurately measure the effective refractive index of each mode in the few-mode fiber at the same time, and well solves the problem that the direct measurement of the effective refractive index of the mode in the few-mode fiber cannot be realized in the prior art.

[0106] Among them, the use of the processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distance and the optical power includes: using the processing unit to obtain at least one maximum value and the distance corresponding to the maximum value from at least two of the optical powers; obtaining the effective refractive index corresponding to each mode in the fiber under test according to the at least one maximum value and the distance corresponding to the maximum value.

[0107] In an embodiment of the present invention, obtaining the effective refractive index corresponding to each mode in the optical fiber to be measured according to the at least one maximum value and the distance corresponding to the maximum value includes: using Formula 1 to Formula 4 to obtain the effective refractive index corresponding to the corresponding mode in the optical fiber to be measured according to the maximum value and the distance corresponding to the maximum value; where, Formula 1 to Formula 4 are as follows in sequence: n 1 sin(θ 1 ) = n 2 sin(θ 2 );

[0108] The n 1 represents the refractive index of the prism of the coupling beam splitting unit at the working wavelength of the light source unit; the θ 1 represents the angle between the light emerging from the exposed surface of the optical fiber to be measured and the upper surface of the grooved spacer block of the coupling beam splitting unit inside the prism; the n 2 represents the refractive index of air at the working wavelength of the light source unit; the θ 2 represents the angle between the light after emerging from the prism and the upper surface of the grooved spacer block; the h 1 represents the distance from the light emergence point on the emergence surface of the prism to the bottom edge of the emergence surface; the d 1 represents the distance from the center point of the exposed surface of the optical fiber to be measured to the bottom edge of the emergence surface; the h 2 represents the distance corresponding to the maximum value; the d 2 represents the distance from the emergence surface to the plane where the optical power detection component in the optical detection unit is located; the n eff represents the effective refractive index; the upper surface of the grooved spacer block refers to the surface adjacent to the prism.

[0109] In an embodiment of the present invention, the distribution order of the modes along h 2 is known in advance and belongs to the characteristics of the optical fiber itself; therefore, according to the above maximum value and the distance corresponding to the maximum value, the effective refractive index corresponding to the corresponding mode in the optical fiber to be measured can be obtained; this will not be elaborated here.

[0110] Next, an example is given for the effective refractive index measurement device and method provided by the embodiments of the present invention. The effective refractive index measurement device can also be called an effective refractive index measurement apparatus. Hereinafter, it will be described with an effective refractive index measurement apparatus.

[0111] In view of the above technical problems, the embodiments of the present invention provide an effective refractive index measurement device and method, which can be specifically implemented as an effective refractive index measurement device and method for modes in a few-mode fiber based on prism coupling, achieving direct, simple, and accurate measurement of the effective refractive indices of various modes in a few-mode fiber simultaneously, solving the problem that the effective refractive indices of modes in a few-mode fiber cannot be accurately and directly measured currently, and having the advantages of being simple and easy to implement and accurate in measurement.

[0112] Specifically, the solution provided by the embodiments of the present invention involves:

[0113] (1) An effective refractive index measurement device for modes in a few-mode fiber, as Figure 1 shown, including a light source unit, a coupling and splitting unit, a light detection unit, and a processing unit;

[0114] (2) An effective refractive index measurement method for modes in a few-mode fiber using the above-mentioned effective refractive index measurement device for modes in a few-mode fiber.

[0115] Specifically, in the effective refractive index measurement device for modes in a few-mode fiber, the light source unit, the coupling and splitting unit, and the light detection unit are sequentially arranged on the optical path, and the processing unit is electrically connected to the light detection unit; the light source unit is used to provide a narrow linewidth continuous laser; the coupling and splitting unit is used to couple out the light of each mode in the fiber under test (corresponding to the above-mentioned fiber to be tested) from the core and split it into different spatial directions and positions; the light detection unit is used to detect the optical power in different spatial directions and positions (corresponding to the above-mentioned the light detection unit can obtain at least two groups of distances from the optical power detection parts in the light detection unit to the plane where the exposed surface of the fiber to be tested is located, and the optical power corresponding to the distances; different ones of the distances correspond to the different spatial directions and positions); the processing unit is used to obtain the electrical signals corresponding to the optical power and spatial position transmitted by the light detection unit and calculate the effective refractive indices of each mode in the fiber under test (corresponding to the above-mentioned the processing unit can obtain the effective refractive indices corresponding to each mode in the fiber to be tested according to the distances and the optical power).

[0116] Optionally, for the effective refractive index measurement device of the modes in the few-mode optical fiber, the working wavelength and laser power of the light source unit are adjustable, and it is used to provide a narrow linewidth continuous laser. The working wavelength range of the light source unit can be continuously adjusted between 400 - 1700 nm, and the laser power can be continuously adjusted between 0 - 1 W. The coupling and splitting unit can be an optical system composed of a slotted pad and a prism. The optical fiber to be measured can be fixed in the groove of the slotted pad and polished to a D shape (to obtain the above-mentioned exposed surface), and the upper cover prism (corresponding to the above prism) is used to couple the light of each mode in the optical fiber to be measured out of the fiber core and split it to different spatial directions and positions. The light detection unit can be composed of a power meter (a specific implementation example of the above-mentioned light power detection component) and a one-dimensional displacement stage, and is used to detect the light power in different spatial directions and positions. The processing unit is used to obtain the electrical signals corresponding to the light power and spatial position transmitted by the light detection unit and calculate the effective refractive index of each mode in the optical fiber to be measured.

[0117] The method for measuring the effective refractive index of the modes in the few-mode optical fiber by applying the above-mentioned effective refractive index measurement device of the modes in the few-mode optical fiber specifically may include the following steps:

[0118] 1) Select an optical fiber to be measured with a length of L, and place it in the coupling and splitting unit of the above-mentioned effective refractive index measurement device of the modes in the few-mode optical fiber. Specifically, embed it in the groove of the slotted pad with uncured glue dripped in advance, and cure the glue to fix it;

[0119] 2) Polish off a part of the cladding of the optical fiber to be measured protruding from the upper surface of the slotted pad to form a D shape (the optical fiber will expose a surface, corresponding to the above-mentioned exposed surface of the optical fiber to be measured). The assembly relationship between the optical fiber to be measured and the coupling and splitting unit is as Figure 5 shown; the left subfigure (cross-sectional schematic diagram) is used to schematically show the optical fiber to be measured placed in the slotted pad, the middle subfigure (cross-sectional schematic diagram) is used to schematically show that the coupling area of the optical fiber to be measured is polished to a D shape, and the right subfigure (cross-sectional schematic diagram) is used to schematically show the upper cover prism. A refractive index matching liquid (corresponding to the above-mentioned refractive index matching liquid layer 11) is dropped on the contact surfaces between the prism, the optical fiber to be measured, and the slotted pad; a represents uncured glue, b represents the part of the cladding that is polished off, the optical fiber to be measured in the middle subfigure is polished into a D shape, and c represents cured glue.

[0120] 3) Connect the light source unit to the input end of the optical fiber to be measured, adjust the output working wavelength and output power of the light source unit to the preset working wavelength and preset output power. The refractive index of the prism at the working wavelength (corresponding to the refractive index of the prism of the above-mentioned coupling and splitting unit at the working wavelength of the light source unit) is n 1 , and the refractive index of air at the working wavelength (corresponding to the refractive index of air at the working wavelength of the above-mentioned light source unit) is n 2 ;

[0121] 4) Place the prism on the upper surface of the grooved pad, and drop the refractive index matching liquid between the prism and the side polished surface of the fiber under test. The positional relationship is as Figure 3 and Figure 4 shown, such that the light emerging from the prism hits the plane where the optical power meter is located. The distance from the center point of the side polished surface of the fiber under test (corresponding to the above-mentioned exposed surface) to the bottom edge of the light-emitting surface of the prism (corresponding to the bottom edge of the above-mentioned light-emitting surface) is d 1 , the distance from the light-emitting surface of the prism (corresponding to the above-mentioned light-emitting surface) to the plane where the optical power meter is located is d 2 , the distance from the light-emitting point of the light on the prism surface (corresponding to the above-mentioned light-emitting surface) to the bottom edge of the light-emitting surface (i.e., the bottom edge of the above-mentioned light-emitting surface) is h 1 , the distance from the optical power meter to the plane of the upper surface of the grooved pad (corresponding to the distance from the optical power detection component in the above-mentioned optical detection unit to the plane of the exposed surface of the fiber to be measured) is h 2 , the angle between the light in the prism and the upper surface of the grooved pad (corresponding to the angle between the light emerging from the exposed surface of the fiber to be measured and the upper surface of the grooved pad of the coupling and splitting unit in the prism) is θ 1 , the angle between the light after emerging from the prism and the upper surface of the grooved pad is θ 2 ;

[0122] 5) Configure the one-dimensional displacement stage (a specific implementation example of the above displacement stage) to move unidirectionally and scan the height information h 2 , and record the optical power P detected by the optical power meter at the corresponding height;

[0123] 6) The processing unit analyzes the optical power P recorded in 5), finds the maximum points (corresponding to the above-mentioned maximum values), and records the corresponding height information h 2 , these points correspond to each mode in the fiber under test. Substitute the height information h 2 into the following equations (corresponding to the above-mentioned Formula 1 to Formula 4) to calculate the effective refractive index n of each mode eff :

[0124]

[0125] where P is a one-dimensional array containing the optical powers corresponding to different heights h 2 ; different modes will be refracted to different heights, but the modes are discrete, so the power is higher where there are modes and lower where there are no modes;

[0126] Specifically, the testing process does not distinguish between modes, and the effective refractive indices of all modes are measured in the same scan. During the measurement process, the optical power information has been obtained. In this solution, the height information corresponding to the extreme points of the optical power information is extracted, which is an array and is substituted into the formula one by one for calculation. What is obtained is the effective refractive index corresponding to the discrete height information.

[0127] In the method for measuring the effective refractive index of modes in the few-mode optical fiber, the length L of the measured few-mode optical fiber is greater than or equal to 10 cm.

[0128] The following is a specific example of this solution. The embodiment of the device for measuring the effective refractive index of modes in the few-mode optical fiber of the present invention is as Figure 1 shown, including a light source unit, a coupling and splitting unit, a light detection unit, and a processing unit arranged in sequence.

[0129] The working wavelength of the light source unit is adjustable and is used to provide a narrow linewidth continuous laser. The working wavelength range can be continuously adjusted between 400 - 1700 nm, and the laser power can be continuously adjusted between 0 - 1 W. The output optical fiber of the light source unit can be a multi-mode optical fiber, which is used to conduct the narrow linewidth continuous laser and generate a mixed light of multiple modes. The multi-mode optical fiber can be a bare optical fiber or a patch cord.

[0130] The coupling and splitting unit is used to couple out the light of each mode in the measured optical fiber from the fiber core and split it into different spatial directions and positions. The coupling and splitting unit is an optical system composed of a slotted spacer and a prism. The material of the slotted spacer can be fused silica, and the slot can be a square slot. The composition of the prism can be BK7 glass. The measured optical fiber can be fixed in the groove of the slotted spacer and polished to a D shape, and then covered with a prism.

[0131] The light detection unit is used to detect the optical power in different spatial directions and positions. The light detection unit can be composed of an optical power meter and a one-dimensional displacement stage. The one-dimensional displacement stage can be an electrically controlled one-dimensional stepping displacement stage. The electrical output end of the optical power meter can be used to connect to the processing unit.

[0132] The processing unit is used to obtain the electrical signals corresponding to the optical power and spatial position transmitted by the light detection unit and calculate the effective refractive index of each mode in the measured optical fiber.

[0133] The method for measuring the effective refractive index of modes in the few-mode optical fiber applying the above device specifically may include the following steps:

[0134] 1) Select a measured optical fiber with a length of L and place it in the coupling and splitting unit of the device for measuring the effective refractive index of modes in the few-mode optical fiber. Specifically, embed it in the groove of the slotted spacer with uncured glue pre-dropped, and cure the glue to fix it.

[0135] Taking the measured few-mode optical fiber as an example of a circular six-mode optical fiber: it supports LP 01 , LP 11 , LP 21 , LP 02 , LP 31 , LP 12 A total of six degenerate modes. The length L of the measured optical fiber is 50 cm, and its input end is equipped with a connector.

[0136] 2) The part of the cladding of the measured optical fiber protruding from the upper surface of the grooved spacer is polished off to form a D shape. The assembly relationship between the measured optical fiber and the coupling and splitting unit is as Figure 5 shown;

[0137] 3) Connect the light source unit to the input end of the measured optical fiber, and adjust the output working wavelength and output power of the light source unit to the preset working wavelength and preset output power. The preset working wavelength can be 1550 nm, and the preset output power can be 10 dBm; the refractive index n of the prism at the working wavelength 1 can be 1.5007, and the refractive index n of air at the working wavelength 2 can be 1.0003;

[0138] 4) Place the prism on the upper surface of the grooved spacer, and drop a refractive index matching liquid between the prism and the side polished surface of the measured optical fiber. The positional relationship is as Figure 3 and Figure 4 shown, so that the light emitted by the prism hits the plane where the optical power meter is located. The distance from the center point of the side polished surface of the measured optical fiber to the bottom edge of the light-emitting surface of the prism is d 1 , the distance from the light-emitting surface of the prism to the plane where the optical power meter is located is d 2 , the distance from the light-emitting point on the surface of the prism to the bottom edge of the light-emitting surface is h 1 , the distance from the optical power meter to the plane where the upper surface of the grooved spacer is located is h 2 , the angle between the light in the prism and the upper surface of the grooved spacer is θ 1 , and the angle between the light after emitting from the prism and the upper surface of the grooved spacer is θ 2 ;

[0139] 5) Configure the one-dimensional displacement stage to move unidirectionally, scan the height information h 2 , and record the optical power P detected by the optical power meter at the corresponding height;

[0140] 6) The processing unit analyzes the optical power P recorded in 5), finds the maximum value points, and records the corresponding height information h 2 . These points correspond to each mode in the measured optical fiber. Substitute the height information h 2 into the following equations to calculate the effective refractive index n of each mode eff :

[0141]

[0142] The test results, the optical power - measurement height information of the emitted light of the fiber under test collected are as follows Figure 6 As shown, it can be seen that there are 6 maximum points. By calculating the height information corresponding to these 6 maximum points, the effective refractive indices corresponding to them are obtained as shown in Table 1:

[0143] Mode <![CDATA[LP 01 > <![CDATA[LP 11 > <![CDATA[LP 21 > <![CDATA[LP 02 > <![CDATA[LP 31 > <![CDATA[LP 12 > <![CDATA[n measured by this solution eff > 1.4537 1.4519 1.4489 1.4477 1.4466 1.4448

[0144] Table 1 Measured values of the effective refractive indices of each mode of the fiber under test

[0145] In summary, the beneficial effects of this solution are as follows:

[0146] 1) The device for measuring the effective refractive index of modes in a few - mode fiber provided by this solution realizes the direct determination of the effective refractive indices of each mode in the few - mode fiber by the selection and design of the light source unit, the coupling and splitting unit, the optical detection unit and the processing unit, and solves the problem that currently it is impossible to directly measure but only indirectly measure the effective refractive indices of each mode in the few - mode fiber.

[0147] 2) The device for measuring the effective refractive index of modes in a few - mode fiber provided by this solution and the method for measuring the effective refractive index of modes in a few - mode fiber based on the device have the advantages of high measurement accuracy and convenient measurement.

[0148] Here, it should be noted that the above - mentioned few - mode fiber refers to a fiber that supports multiple guided - wave modes; the mode effective refractive index is a characteristic parameter of each guided - wave mode in the fiber.

[0149] The embodiment of the present invention also provides an effective refractive index measurement device, which is applied to the above - mentioned effective refractive index measurement equipment, as Figure 7 shown. The device includes:

[0150] A first input module 71, configured to input an optical signal into the fiber under test by using the light source unit to obtain the light of each mode in the fiber under test;

[0151] A coupling and splitting module 72, configured to couple the light of each mode in the fiber under test out of the core by using the coupling and splitting unit and split it to different spatial directions and positions;

[0152] A first detection module 73, configured to detect the optical power in different spatial directions and positions by using the optical detection unit to obtain at least two groups of distances from the optical power detection components in the optical detection unit to the plane where the exposed surface of the fiber under test is located, and the optical power corresponding to the distances;

[0153] The first processing module 74 is configured to use a processing unit to obtain the effective refractive index corresponding to each mode in the optical fiber under test according to the distance and the optical power.

[0154] The effective refractive index measuring device provided by the embodiment of the present invention inputs an optical signal into the optical fiber under test by using a light source unit to obtain the light of each mode in the optical fiber under test; uses a coupling and splitting unit to couple the light of each mode in the optical fiber under test out of the fiber core and split it into different spatial directions and positions; uses a light detection unit to detect the optical power in different spatial directions and positions, obtains at least two distances from the light power detection components in the light detection unit to the plane where the exposed surface of the optical fiber under test is located, and the optical power corresponding to the distance; uses a processing unit to obtain the effective refractive index corresponding to each mode in the optical fiber under test according to the distance and the optical power; can directly, simply and accurately measure the effective refractive index of each mode in a few-mode optical fiber at the same time, and well solves the problem that the direct measurement of the effective refractive index of the mode in a few-mode optical fiber cannot be realized in the prior art.

[0155] Among them, the step of using a processing unit to obtain the effective refractive index corresponding to each mode in the optical fiber under test according to the distance and the optical power includes: using a processing unit to obtain at least one maximum value and the distance corresponding to the maximum value from at least two of the optical powers; obtaining the effective refractive index corresponding to each mode in the optical fiber under test according to the at least one maximum value and the distance corresponding to the maximum value.

[0156] In the embodiment of the present invention, the step of obtaining the effective refractive index corresponding to each mode in the optical fiber under test according to the at least one maximum value and the distance corresponding to the maximum value includes: using Formula 1 to Formula 4 to obtain the effective refractive index corresponding to the corresponding mode in the optical fiber under test according to the maximum value and the distance corresponding to the maximum value; where, Formula 1 to Formula 4 are in turn: n 1 sin(θ 1 ) = n 2 sin(θ 2 );

[0157] The n 1 represents the refractive index of the prism of the coupling and splitting unit at the working wavelength of the light source unit; the θ 1 represents the angle between the light transmitted from the exposed surface of the optical fiber under test in the prism and the upper surface of the grooved pad of the coupling and splitting unit; the n 2 represents the refractive index of air at the working wavelength of the light source unit; the θ 2represents the angle between the light emerging from the prism and the upper surface of the slotted spacer; the h 1 represents the distance from the light-emitting point on the light-emitting surface of the prism to the bottom edge of the light-emitting surface; the d 1 represents the distance from the center point of the exposed surface of the fiber under test to the bottom edge of the light-emitting surface; the h 2 represents the distance corresponding to the maximum value; the d 2 represents the distance from the light-emitting surface to the plane where the optical power detection component in the optical detection unit is located; the n eff represents the effective refractive index; the upper surface of the slotted spacer refers to the surface adjacent to the prism.

[0158] Among them, the implementation embodiments of the above effective refractive index measurement method are all applicable to the embodiments of this effective refractive index measurement device, and the same technical effects can also be achieved.

[0159] An embodiment of the present invention further provides an effective refractive index measurement device, including the components included in the above effective refractive index measurement device, such as Figure 8 As shown, the device further includes: a processor 81 and a transceiver 82;

[0160] The processor 81 is configured to input an optical signal into the fiber under test by using a light source unit to obtain the light of each mode in the fiber under test;

[0161] Using a coupling and splitting unit to couple the light of each mode in the fiber under test out of the fiber core and split it into different spatial directions and positions;

[0162] Using an optical detection unit to detect the optical power in different spatial directions and positions, obtaining at least two groups of distances from the optical power detection components in the optical detection unit to the plane where the exposed surface of the fiber under test is located, and the optical power corresponding to the distances;

[0163] Using a processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distances and the optical power.

[0164] The effective refractive index measurement device provided by the embodiments of the present invention inputs an optical signal into a fiber under test by using a light source unit to obtain the light of each mode in the fiber under test; uses a coupling and splitting unit to couple the light of each mode in the fiber under test out of the core and split it to different spatial directions and positions; uses a light detection unit to detect the optical power in different spatial directions and positions, obtains at least two distances from the light power detection components in the light detection unit to the plane where the exposed surface of the fiber under test is located, and the optical power corresponding to the distances; uses a processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distances and the optical power, and can directly, simply and accurately measure the effective refractive index of each mode in a few-mode fiber at the same time, which well solves the problem that the direct measurement of the effective refractive index of the mode in a few-mode fiber cannot be realized in the prior art.

[0165] Among them, the process of using the processing unit to obtain the effective refractive index corresponding to each mode in the fiber under test according to the distances and the optical power includes: using the processing unit to obtain at least one maximum value and the distance corresponding to the maximum value from at least two of the optical powers; and obtaining the effective refractive index corresponding to each mode in the fiber under test according to the at least one maximum value and the distance corresponding to the maximum value.

[0166] In the embodiments of the present invention, the process of obtaining the effective refractive index corresponding to each mode in the fiber under test according to the at least one maximum value and the distance corresponding to the maximum value includes: using Formula 1 to Formula 4 to obtain the effective refractive index corresponding to the corresponding mode in the fiber under test according to the maximum value and the distance corresponding to the maximum value; where Formula 1 to Formula 4 are in sequence: n 1 sin(θ 1 )=n 2 sin(θ 2 );

[0167] The n 1 represents the refractive index of the prism of the coupling and splitting unit at the working wavelength of the light source unit; the θ 1 represents the angle between the light transmitted from the exposed surface of the fiber under test in the prism and the upper surface of the grooved pad of the coupling and splitting unit; the n 2 represents the refractive index of air at the working wavelength of the light source unit; the θ 2 represents the angle between the light after exiting the prism and the upper surface of the grooved pad; the h 1 represents the distance from the exit point of the light on the exit surface of the prism to the bottom edge of the exit surface; the d 1represents the distance from the center point of the exposed surface of the optical fiber to be measured to the bottom edge of the exit surface; the h 2 represents the distance corresponding to the maximum value; the d 2 represents the distance from the exit surface to the plane where the optical power detection component in the optical detection unit is located; the n eff represents the effective refractive index; the upper surface of the grooved spacer refers to the surface adjacent to the prism.

[0168] Among them, the implementation embodiments of the above-mentioned effective refractive index measurement method are all applicable to the embodiments of this effective refractive index measurement device, and the same technical effects can also be achieved.

[0169] An embodiment of the present invention also provides an effective refractive index measurement device, including a memory, a processor, and a program stored on the memory and executable on the processor; when the processor executes the program, the above-mentioned effective refractive index measurement method is implemented.

[0170] Among them, the implementation embodiments of the above-mentioned effective refractive index measurement method are all applicable to the embodiments of this effective refractive index measurement device, and the same technical effects can also be achieved.

[0171] An embodiment of the present invention also provides a readable storage medium, on which a program is stored, and when the program is executed by a processor, the steps in the above-mentioned effective refractive index measurement method are implemented.

[0172] Among them, the implementation embodiments of the above-mentioned effective refractive index measurement method are all applicable to the embodiments of this readable storage medium, and the same technical effects can also be achieved.

[0173] It should be noted that many functional components described in this specification are referred to as modules in order to more particularly emphasize the independence of their implementation methods.

[0174] In the embodiments of the present invention, a module can be implemented by software so as to be executed by various types of processors. For example, an identifiable executable code module can include one or more physical or logical blocks of computer instructions. For example, it can be constructed as an object, a process, or a function. Nevertheless, the executable code of the identified module does not need to be physically located together, but can include different instructions stored in different locations. When these instructions are logically combined together, they constitute the module and achieve the specified purpose of the module.

[0175] In fact, the executable code module can be a single instruction or many instructions, and can even be distributed over multiple different code segments, distributed among different programs, and distributed across multiple memory devices. Similarly, the operation data can be identified within the module, and can be implemented in any suitable form and organized within any suitable type of data structure. The operation data can be collected as a single data set, or can be distributed at different locations (including on different storage devices), and can at least partially exist only as electronic signals in a system or network.

[0176] When the module can be implemented by software, considering the level of existing hardware technology, for the modules that can be implemented by software, without considering the cost, those skilled in the art can build corresponding hardware circuits to implement the corresponding functions. The hardware circuits include conventional very large scale integration (VLSI) circuits or gate arrays, and existing semiconductors such as logic chips and transistors, or other discrete components. The module can also be implemented using programmable hardware devices, such as field programmable gate arrays, programmable array logic, programmable logic devices, etc.

[0177] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An effective refractive index measuring device, characterized in that, it includes: a light source unit, a coupling and splitting unit, and a light detection unit that are sequentially arranged on the optical path; and a processing unit electrically connected to the light detection unit; wherein, the light source unit can be connected to the input end of the fiber to be measured; the coupling and splitting unit can clamp the fiber to be measured and couple out the light of each mode in the fiber to be measured from the core, and split it to different spatial directions and positions; the light detection unit can obtain at least two sets of distances from the light power detection components in the light detection unit to the plane where the exposed surface of the fiber to be measured is located, and the light power corresponding to the distances; the different distances correspond to the different spatial directions and positions; the processing unit can obtain the effective refractive index corresponding to each mode in the fiber to be measured according to the distance and the light power.

2. The effective refractive index measuring device according to claim 1, characterized in that, the coupling and splitting unit includes: a grooved pad and a prism covering the grooved pad; wherein, the fiber to be measured is fixed in the groove of the grooved pad, and the exposed surface of the fiber to be measured is adjacent to the prism.

3. The effective refractive index measuring device according to claim 2, characterized in that, a refractive index matching liquid layer is provided between the exposed surface of the fiber to be measured and the prism; the refractive index matching liquid layer makes the light emitted by the prism hit the plane where the light power detection component in the light detection unit is located.

4. The effective refractive index measuring device according to any one of claims 1 to 3, characterized in that, the light detection unit further includes: a displacement stage connected to the light power detection component; wherein, the light power detection component can move vertically on the displacement stage.

5. The effective refractive index measuring device according to claim 4, characterized in that, the displacement stage includes a base and a rod arranged on the base; the light power detection component is sleeved on the rod.

6. An effective refractive index measuring method applied to the effective refractive index measuring device according to any one of claims 1 to 5, characterized in that, the method includes: using the light source unit to input an optical signal into the fiber to be measured to obtain the light of each mode in the fiber to be measured; using the coupling and splitting unit to couple out the light of each mode in the fiber to be measured from the core and split it to different spatial directions and positions; using the light detection unit to detect the light power in the different spatial directions and positions, to obtain at least two sets of distances from the light power detection components in the light detection unit to the plane where the exposed surface of the fiber to be measured is located, and the light power corresponding to the distances; using the processing unit to obtain the effective refractive index corresponding to each mode in the fiber to be measured according to the distance and the light power.

7. The effective refractive index measuring method according to claim 6, characterized in that, the step of using the processing unit to obtain the effective refractive index corresponding to each mode in the fiber to be measured according to the distance and the light power includes: using the processing unit to obtain at least one maximum value and the distance corresponding to the maximum value from at least two of the light powers; Based on the at least one maximum value and the distance corresponding to the maximum value, the effective refractive indices corresponding to each mode in the optical fiber to be measured are obtained.

8. The effective refractive index measurement method according to claim 7, wherein, the step of obtaining the effective refractive indices corresponding to each mode in the optical fiber to be measured based on the at least one maximum value and the distance corresponding to the maximum value includes: Using Formula 1 to Formula 4, based on the maximum value and the distance corresponding to the maximum value, the effective refractive indices corresponding to the corresponding modes in the optical fiber to be measured are obtained; wherein, Formula 1 to Formula 4 are as follows in sequence: n 1 sin(θ 1 ) = n 2 sin(θ 2 ); The said n 1 represents the refractive index of the prism of the said coupling beam splitting unit at the operating wavelength of the said light source unit; the said θ 1 represents the angle between the light emerging from the exposed surface of the said optical fiber under test within the said prism and the upper surface of the grooved pad of the said coupling beam splitting unit; the said n 2 represents the refractive index of air at the operating wavelength of the said light source unit; the said θ 2 represents the angle between the light emerging from the said prism and the upper surface of the grooved pad; the said h 1 represents the distance from the light exit point on the exit surface of the said prism to the bottom edge of the exit surface; the said d 1 represents the distance from the center point of the exposed surface of the said optical fiber under test to the bottom edge of the exit surface; the said h 2 represents the said distance corresponding to the said maximum value; the said d 2 represents the distance from the said exit surface to the plane where the optical power detection component in the said light detection unit is located; the said n eff represents the said effective refractive index; The upper surface of the grooved spacer refers to the surface adjacent to the prism.

9. An effective refractive index measurement device, applied to the effective refractive index measurement equipment according to any one of claims 1 to 5, wherein, the device includes: A first input module, configured to input an optical signal into the optical fiber to be measured by using a light source unit, and obtain the light of each mode in the optical fiber to be measured; A coupling and splitting module, configured to couple the light of each mode in the optical fiber to be measured out of the fiber core by using a coupling and splitting unit, and split it into different spatial directions and positions; A first detection module, configured to detect the optical power in different spatial directions and positions by using an optical detection unit, obtain the distances from the optical power detection components in at least two groups of the optical detection units to the plane of the exposed surface of the optical fiber to be measured, and the optical power corresponding to the distances; A first processing module, configured to obtain the effective refractive indices corresponding to each mode in the optical fiber to be measured by using a processing unit according to the distances and the optical power.

10. The effective refractive index measurement device according to claim 9, wherein, the step of obtaining the effective refractive indices corresponding to each mode in the optical fiber to be measured by using a processing unit according to the distances and the optical power includes: Using a processing unit to obtain at least one maximum value and the distance corresponding to the maximum value from at least two of the optical powers; Based on the at least one maximum value and the distance corresponding to the maximum value, the effective refractive indices corresponding to each mode in the optical fiber to be measured are obtained.

11. The effective refractive index measurement device according to claim 10, wherein, the step of obtaining the effective refractive indices corresponding to each mode in the optical fiber to be measured based on the at least one maximum value and the distance corresponding to the maximum value includes: Using Formula 1 to Formula 4, based on the maximum value and the distance corresponding to the maximum value, the effective refractive indices corresponding to the corresponding modes in the optical fiber to be measured are obtained; wherein, Formula 1 to Formula 4 are as follows in sequence: n 1 sin(θ 1 ) = n 2 sin(θ 2 ); The said n 1 represents the refractive index of the prism of the said coupling and splitting unit at the operating wavelength of the said light source unit; the said θ 1 represents the angle between the light emerging from the exposed surface of the said fiber under test within the prism and the upper surface of the grooved spacer of the said coupling and splitting unit; the said n 2 represents the refractive index of air at the operating wavelength of the said light source unit; the said θ 2 represents the angle between the light emerging from the prism and the upper surface of the grooved spacer; the said h 1 represents the distance from the light exit point on the exit surface of the prism to the bottom edge of the exit surface; the said d 1 represents the distance from the center point of the exposed surface of the said fiber under test to the bottom edge of the exit surface; the said h 2 represents the said distance corresponding to the said maximum value; the said d 2 represents the distance from the exit surface to the plane where the optical power detector in the said light detection unit is located; the said n eff represents the said effective refractive index; The upper surface of the grooved spacer refers to the surface adjacent to the prism.

12. An effective refractive index measurement equipment, including the components included in the effective refractive index measurement equipment according to any one of claims 1 to 5, wherein, the equipment further includes: a processor and a transceiver; The processor is configured to input an optical signal into the optical fiber to be measured by using a light source unit, and obtain the light of each mode in the optical fiber to be measured; The optical modes in the fiber under test are coupled out of the core by a coupling and splitting unit, and split to different spatial directions and positions; An optical detection unit is used to detect the optical powers in different spatial directions and positions, obtaining at least two sets of distances from the optical power detection components in the optical detection unit to the plane where the exposed surface of the fiber under test is located, and the optical powers corresponding to the distances; A processing unit is used to obtain the effective refractive indices corresponding to the optical modes in the fiber under test according to the distances and optical powers.

13. An effective refractive index measurement device, comprising a memory, a processor, and a program stored on the memory and operable on the processor; Characterized in that When the processor executes the program, the effective refractive index measurement method according to any one of claims 6 to 8 is implemented.

14. A readable storage medium, on which a program is stored, Characterized in that When the program is executed by a processor, the steps in the effective refractive index measurement method according to any one of claims 6 to 8 are implemented.

Images